1. Field of the Inventon
The present invention relates to a seat apparatus for vehicles, and particularly to an improvement in a frame of the seat apparatus.
2. Description of the Prior Art
A conventional seat apparatus for vehicles includes a seat cushion and a seat back. As shown in FIGS. 9 and 10, the conventional seat cushion and the seat back are respectively mounted on a frame 10a having enough mechanical strength. In vehicles having the conventional seat apparatus, the fram 10a is typically made of plastics so as to be made lighter and to improve fuel economy of the vehicle.
However, the frame 10a is usually shaped so as to extend upwardly along the outer edges as shown in FIGS. 9 and 10 so that the frame 10a should support the seat cushion 3 or the seat back (not shown) without any sliding movement thereof. Accordingly, since plastics do not provide sufficient mechanical strength, the frame 10a must be formed so that the outer upward extending shape lacks bending and improves torsional rigidity. Consequently, the plastic frame must be formed thick. Therefore, since the frame 10a should have enough thickness, the light weight for the frame 10a is not expected.
As mentioned above, the frame 10a made of plastics is easily deformed. Therefore, when the vehicle crashed, the front end of frame 10a is deformed by the load from the occupant so that in spite of wearing the seat belt, the occupant will be shifted along the seat between the seat belt and the seat cushion and be pushed out of the seat.